Alternative Energy – Nuclear Energy (Fission)

Scientists, politicians, and everyday citizens are starting to realize the undeniable fact that fossil fuel is becoming an unreliable source for providing energy. The inefficiency energy output from fossil fuel, the environmental harm and contribution to global warming from the emission of the combustion of fossil fuel, and the inevitability of using all of the fossil fuels have resulted in researchers and scientists on the look for an alternative and long-lasting source of energy; hydroelectric dams, wind mill farms, and solar panels are just to name a few. From the start of the late 20th century, researchers and scientists have turned their attention to another alternative energy: nuclear energy.

Despite the unfamiliarity of the term “nuclear energy”, nuclear energy works in a similar fashion as a classic coal-burning plant. As its name implies, nuclear energy is focused onto the atomic level. Simplified, nuclear energy is divided into two types: fusion and fission. Nuclear fusion is the process in which two atoms join together to form a single heavier atom. During this process a massive amount of energy is released. However, the energy released is so large that it is impossible or extremely difficult to control with out current technology so that there is a positive yield. That being said, once the energy from a controlled nuclear fusion can be harnessed, then theoretically, the world’s energy crisis will be solved. Until then, nuclear fission is looked to.

Nuclear fission is the process in which a single atom splits into two lighter atoms. As this occurs, energy is released in the forms of neutrons, gamma, and other forms of energy. The energy released from this splitting is much easily captured compared to nuclear fusion. A simplified description of the workings of a nuclear plant is provided. For more details, refer to the Physics Concept Section. Surprisingly, a nuclear (fission) plant works similar to a coal(fossil fuel) plant. When Uranium 235 undergoes nuclear fission, the energy produced is captured and transferred via control rods. These control rods are able to direct the heat produced from the fission reaction to a water source where the water is turned into steam and used to rotate turbines. This mechanical movement of turbine can be translated into different forms of energy.

In theory, this would be an excellent alternative energy. However, many problems arise in social implications (see social implications for further details). To name a few, they are: the possibility of a disastrous nuclear meltdown, nuclear radiation exposure for workers, and the treatment of nuclear waste. As a quick summary before further detail, nuclear energy, particularly fission, has the potential to be an active replacement for fossil fuel. However, it is still limited in its development and progresses must be made with caution and checks.

Nuclear fission can be considered to be a radioactive decay or reaction where the nucleus of the main atom begins to split into smaller components. Due to the splitting of the atom what results from this process is the neutrons and protons along with the release of immense amount of energy in the form of Gamma Rays. Gamma Rays are beams that contain high energy photons and have the ability to travel great distances in the air. Once the fission process takes place one big nucleus becomes two new nucleus that have similarities but their sizes will somewhat vary. Most fission that happens in the world today are considered binary fission which means that two products are created.

Fissile Isotopes

What is important to first know is that fissile isotopes of elements have the ability to go through the process of fission. What also needs to be considered when dealing with nuclear fission is the speed of the neutron that is bombarding the isotope. Due to the factor of speed it can have the ability to start the process of fission in elements that a slow pace neutron would not cause.

An example of a nuclear fission that is used in the world today is an induced fission and this process starts out when a neutron is absorbed by uranium-235 which then forces this atom to become a uranium-236 nucleus. With the immense amount of kinetic energy that is produced by the neutron the uranium-236 nucleus that was created becomes its lighter elements and the strong gamma rays are produced along with more free neutrons.

Nuclear fission does not necessarily need to occur with the barrage of neutrons when going through the process of radioactive decay. This type of fission is known as spontaneous fission and mainly happens in heavy atoms.

The YouTube clip that follows gives an excellent model and the process of nuclear fission and shows how the neutron is put into uranium-235 and the outcome of energy:

When dealing with the reactor the fuel present are sealed within a metal jacket.

When the process of fission starts the fragments will break apart from the nucleus itself will be in the fuel. After that the kinetic energy will start behaving as thermal energy it must be noted that there will also be a few neutron that will be released through the process and will move alongside the kinetic energy. These free neutron will also will be attempted to slow down so there will be the possibility of the neutrons being absorbed by the excess fuel which can start many more fission reactions. This whole idea can be considered to be chain reaction because more neutrons will become free and react with the fuel. What is important to know is that electromagnetic radiation being present in gamma rays will also be products of nuclear fission. From this any transformation of energy or nuclear energy along with binding energy will be converted into kinetic energy and or electromagnetic Radiation. http://www.youtube.com/watch?v=OOf-tIj-JQUthis – this YouTube video gives a step by step process for the nuclear fission in reactors.

The greatest example that can be used when related to nuclear fission is the decay of Uranium-235, in which the nucleus absorbs a neutron, consequently creating Uranium-236 in a highly existed state. This Uranium-236 then follows to undergo fission in which this nucleus is split into two parts. Interestingly enough, these two new nuclei emit two neutrons, leaving Xe-140 and Sr-94 as the remaining products of this fission. However, it is important to note that these two products also will undergo beta decay until it finally reaches a stable nucleus.

Essentially nuclear fission is the undergoing process of which the nuclei of elements that are of nuclear-level risk break apart by accepting a neutron into itself. Consequently the nuclei in question will split and travel in their own directions to be split again, however, during this process a lot of energy is released, which is why nuclear fission is so popular when it comes to armament. But it is important to note that two neutrons will cause a domino effect where they will end up striking another nearby nuclear molecule, thus causing it to break and continue the cycle. This all happens so fast that people really just seem like it is instantaneous and happening all at once, even though in fact it is not. It is really just like a chain reaction once it gets started because it is like a little kid. First it tells two close friends a secret, but those friends end up telling their friends, and those friends find out from other friends. It’s like a wave, in which starts out small, begins to spread out wider and wider until there is some interference, whether it is constructive or destructive. If you want to summarize nuclear fission in one definition, it is the splitting of the nucleus of an atom into smaller portions by having a neutron collide with it.

In regards to nuclear reactors, nuclear fission occurs and the energy released heats up water in a tank. In turn the heated water will be converted into steam, and that steam proceeds to run turbines, and those turbines generate energy!!!! However, it is important to note that nuclear reactors and fission will also accumulate radioactive waste, and radioactivity is something that has contributed to cancer all over the world, a primary example being the events following the atomic bombing of Hiroshima in which millions of Japanese citizens developed cancer and or deformities throughout the next several generations.

Key Terms

Neutron-A subatomic particle that has no charge at all but has the same mass a proton

Nucleus-The main part of an atom that is positively charged and has most of it mass present there.

Fission– The method of splitting one big nucleus in tow smaller fragments.

Kinetic Energy– A form of energy that is due to movement

Binding Energy-The energy that is required to keep a nucleus together

Fissile Isotopes-A substance that has capability of going through chain reactions of nuclear fission.

Gamma Rays-An electromagnetic radiation that has the capability to penetrate very thick substances.

Electromagnetic Radiation– Radiation that includes gamma rays and where electric and magnetic field are in sync

Pros of Nuclear Fission Energy

Large power-generating capacity meet industrial and city needs as opposed to lower-power energies like solar that may only meet local or residential needs

Lower carbon dioxide and greenhouse gases released into the atmosphere in power generation

High construction costs due to complex radiation containment systems and procedures

Unknown and high-known risks in an accident

Long construction time

Waivers are required to limit liability of companies in the event of an accident

Uranium sources are finite as other fuel sources such as coal and are expensive to mine, refine, and transport

Nuclear wastes last 200-500 thousand years

Few long-term waste storage sites

Societal Implications

Nuclear power is considered to be a possible alternative to fossil fuels. This is mainly because it is now being labeled as a more environmentally beneficial solution due to its low emission of greenhouse gases during electricity generation. However, nuclear energy is accepted as a dangerous, potentially problematic but manageable source of generating electricity. Expensive solutions are needed to contain, control, and shield both people and the environment from the potentially harmful effects of nuclear waste and maintenance materials, an extension of nuclear fission energy.

Radioactivity and the dangers of nuclear waste:

Radiation is spread throughout the environment via the planet’s water cycle. When radioactive waste mixes with water, it is transferred through the entire cycle, allowing surrounding vegetation and local marine and animal life to ingest and absorb the radiation. Furthermore, radiation can also spread in the air and can be deposited on people, plants, animals, and soil. The ingestion or inhalation of the wastes can stay in a person for much longer than a life time depending on the half-life of the radiation. Most radioactive materials have half-lives of more than 1000 years.

In detail analysis of the potential benefits and hazards of nuclear energy sources (fission):

Little Pollution

The pollution produced from fossil fuel-burning plants is at dangerous levels. Carbon dioxide, which deplete the protection of the ozone, is being produced by burning coal, gas, and oil. Unlike nuclear power plants, coal-burning plants emit more radioactive material and radiation to the air, creating harmful byproducts like sulfuric acid. As well, where the fossil fuels are running out, sulfurous coal is used to replenish its scarce quantity. This type of coal produces more pollution than the coal previously used. Large reserves of uranium can serve to replace the sulfurous coal being used today.

Safety

Nuclear energy facilities produce an estimated 250 000 tons of carbon dioxide during its lifetime. In contrast, coal-fired plants produce close to 26 billion tons of carbon dioxide every year in the U.S. Soot that causes lung diseases, sulfur dioxide and nitrogen oxides that causes smog and acid rain, and mercury that contaminates fish are emitted in addition to carbon dioxide in coal-fired plants. In an analysis, it was determined that coal kills 4000 times as many people as nuclear power. As of 2010, coal provided the U.S. close to 50% of its electricity whereas nuclear energy provided about 20%.

“The creation of huge quantities of long-lived radioactive waste is the most formidable problem facing the nuclear power industry today. The difficulty of waste disposal was not considered to be a big problem during the time when power plants were first introduced; it was assumed that waste could be recycled or buried. Unfortunately, finding safe ways of storing radioactive wastes so that they do not leak radiation into the environment has proved to be a much more difficult task than anticipated.”

Innovation and research have led to better methods on decreasing waste volume and separating the waste by decay rate more efficiently. On the other hand, in addition to the developments on waste storage, alternative techniques regarding the disposal methods of nuclear wastes remain controversial and are far from complete. Although hazards of radioactive waste are less visible than other issues pertaining to nuclear energy they are no less dangerous, and decisions made concerning this waster will be felt far into the future. In the wake of the Fukushima disaster, one can only infer the future implications of nuclear energy in a world where alternative energy sources are an inevitable and vital asset to the continuation of everyday life.